The main components of a laser light transceiver disclosed in Patent Literature 1 shown below are as follows:
(1) a laser light source that outputs a laser light beam,
(2) a polarization beam splitter that allows the laser light beam outputted from the laser light source to pass therethrough,
(3) a ¼ wavelength plate that allows the laser light beam passing through the polarization beam splitter to pass therethrough, and
(4) a light receiver that receives a reflected light beam of the laser light beam, the reflected light beam being reflected by a target and returning thereto.
The laser light beam passing through the above-mentioned ¼ wavelength plate is irradiated to a target existing in the space, and a reflected light beam of the laser light beam, the reflected light beam being reflected by the target and returning to the ¼ wavelength plate, passes through the ¼ wavelength plate again.
After the reflected light beam of the laser light beam passes through the ¼ wavelength plate, its polarization is rotated by 90 degrees with respect to that of the laser light beam at the time of being outputted from the laser light source. Accordingly, the reflected light beam of the laser light beam is reflected by the polarization beam splitter and received by a light receiver disposed in a direction different from that in which the laser light source is disposed.
Further, in the laser light transceiver disclosed in Patent Literature 1, a scanner optical element is mounted in order to enable observations in two eye directions, and the laser light beam is scanned by causing a scanner control device to mechanically control the scanner optical element.
The scanner optical element is comprised of a galvanometer mirror, and the scanner control device includes a motor control device that drives the galvanometer mirror.
Patent Literature 2 shown below discloses a laser light transceiver that splits a laser light beam outputted from a laser light source into two beams by using a polarization beam splitter in order to enable observations in two eye directions.
The polarization beam splitter splits the laser light beam outputted from the laser light source into a beam having p polarization and a beam having s polarization, and can split the laser light beam into the beams in two directions.
The polarization beam splitter does not include any movable member which might be broken and can split the laser light beam into the beams in two directions without performing any mechanical control.